1. Field of the Invention
The present invention relates to an apparatus for cleaning a squeeze roller of a liquid printer, and more particularly, to an apparatus for cleaning a squeeze roller of a liquid printer in which the structure of a blade is improved to improve the efficiency in cleaning and extend the life span of the blade.
2. Description of the Related Art
A liquid electrophotographic printer prints an image by forming an electrostatic latent image by scanning a laser beam on a photosensitive medium, developing the image with a developer including toner of a predetermined color using a developing unit and transferring the developed image to a print medium.
The liquid electrophotographic printer, as shown in FIG. 1, includes a laser scanning unit (LSU) for forming an electrostatic latent image on a photosensitive medium 10 and a developing unit 20 for forming an image corresponding to the electrostatic latent image.
The developing unit 20 includes a developing vessel 21 and a developing roller 23 which is disposed to face the photosensitive medium 10 such that a predetermined gap G exists therebetween. The apparatus further includes a cleaning roller 25 for removing developer adhering to the outer circumferential surface of the developing roller 23 and an injector 27 for injecting developer containing toner and a carrier into the gap G is a squeeze roller 29 for separating the toner and the carrier by closely pressing the photosensitive medium 10, and a squeeze roller cleaning apparatus 30 for cleaning off the developer adhering to the squeeze roller 29 when a drip-line is removed.
The conventional squeeze roller cleaning apparatus 30, as shown in FIG. 2, includes a blade 31 contacting the outer circumferential surface of the squeeze roller 29 slanted at a predetermined angle. The apparatus further includes, a blade holder 33 fixedly holding the blade 31, and a spanking mechanism 35 for removing a holding volume Vh of the developer remaining between the blade 31 and the squeeze roller 29 by allowing the blade holder 33 to repeatedly pivot a plurality of times. As shown in FIG. 3, the blade 31 is formed of a single rubber member. To prevent a phenomenon in which a surface of a leading edge 31a of the blade 31 contacts the squeeze roller 29 since the blade 31 bends excessively by the rotation of the squeeze roller 29 (hereinafter, referred to as the overturn of the blade), the blade 31 is disposed in a trailing direction with respect to the rotational direction of the squeeze roller 29 in a drip-line removing mode.
To embody the above squeeze roller cleaning apparatus, in the developing unit 20, the pressing force and rotational direction of the squeeze roller 29 varies according to each of a home position, a development mode, and a drip-line removing mode. In the development mode, the pressing force between the squeeze roller 29 and a squeeze backup roller 29' is greatest and the squeeze roller 29 rotates in the direction the photosensitive medium 10 rotates by being passively rotated by the photosensitive medium 10. The squeeze roller 29 squeezes and separates most of the carrier from the developer adhering to the photosensitive medium 10 so as to form a film of the developer. In this mode, the blade 31 is disposed to be separated from the squeeze roller 29.
In the drip-line removing mode, a relatively weak force is applied between the squeeze roller 29 and the squeeze backup roller 29' compared to the development mode and the squeeze roller 29 rotates in a direction opposite to that which the photosensitive medium 10 proceeds. The blade 31 contacts the squeeze roller 29 and cleans the carrier adhering to the squeeze roller 29.
The squeeze roller cleaning apparatus for the conventional liquid printer having the above structure has the following disadvantages.
First, since a rubber member vulnerable to abrasion is adopted, the blade requires replacement after printing about 10,000 sheets of paper.
Second, since the blade is disposed in the trailing direction to prevent the overturn of the blade, the holding volume is generated due to the developer remaining between the blade and the squeeze roller so that the efficiency in cleaning is lowered.
Third, since a spanking mechanism for removing the holding volume is needed, the number of parts and the number of assembly steps increases.